ISO 15176:2019
(Main)Guidance on characterization of excavated soil and other materials intended for re-use
Guidance on characterization of excavated soil and other materials intended for re-use
This document provides guidance on the range of tests that could be necessary to characterize soil and other soil materials intended to be re-used, with or without preliminary treatment (e.g. screening to remove over large material). It is intended to be of use in determining the suitability of soil materials for re-use (see 3.4.1), and the assessment of the environmental impacts that might arise from re-use. It takes into account the different requirements of topsoil, sub-soil and other soil materials such as sediments or treated soils. International Standard methods are listed that might be of use for characterization. Soil materials include natural soils and other materials (e.g. fill, made ground) excavated, stripped, or otherwise removed from their original in-ground or above-ground location (e.g. stockpile), dredged materials, manufactured soils, and soil treated to remove or destroy contaminants. For manufactured soils, which are often made using excavated materials together with other materials such as "green waste", the characteristics of the components and of the manufactured product might need to be determined. NOTE The terms "excavated soil" and "excavated soil materials" are used for brevity throughout the document to embrace the range of materials covered. An overriding principle governing the guidance provided in this document is that when there is to be no change in intended land use at the target site, imported soil materials cannot lead to a permanent reduction in performance of relevant soil functions. The guidance provided is intended to cover a range of possible end uses, including: — play areas for small children, including nursery schools, kindergartens, etc.; — schools; — gardens and other residential areas; — allotments; — horticulture; — agriculture; — forestry; — recreational areas, e.g. parks, sport fields; — restoration of damaged ecosystems; — mining and industrial sites; — construction sites; — road and rail constructions. It is not applicable to the placement of soil materials in an aqueous environment or to restore underground workings. It does not address geotechnical requirements when soil materials are to be used as construction material. NOTE The sensitive end uses listed above such as play areas for small children, schools, gardens, agriculture and recreational areas require particular care, particularly when excavated soils are derived from contaminated sites.
Lignes directrices sur la caractérisation de la terre excavée et d'autres matériaux du sol destinés à la réutilisation
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 15176
Second edition
2019-06
Guidance on characterization of
excavated soil and other materials
intended for re-use
Lignes directrices sur la caractérisation de la terre excavée et d'autres
matériaux du sol destinés à la réutilisation
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative reference . 2
3 Terms and definitions . 2
3.1 Types of soil and other soil materials . 2
3.2 Soil characteristics . 4
3.3 Land and sites . 5
3.4 Utilization, reclamation and treatment . 5
3.5 Assessment . 6
4 Characterization of soil materials and sites. 7
4.1 General . 7
4.2 Investigation strategies . 9
4.3 Sampling strategies .10
4.3.1 General considerations .10
4.3.2 Sampling in situ soil materials .13
4.3.3 Sampling sediments .13
4.3.4 Sampling stockpiles of untreated or treated soil materials .14
4.3.5 Sampling materials arising from a process-based remediation method .14
4.3.6 Sampling manufactured soils .14
4.3.7 Sampling soil materials after placement at the target site .14
4.3.8 Sampling the water environment .14
4.4 Characterization of soil materials .14
4.4.1 General.14
4.4.2 Description of source and target sites .15
4.4.3 Chemical characterization including basic characteristics .17
4.4.4 Physical characteristics .22
4.4.5 Biological characteristics .22
5 Data quality, handling and evaluation .23
6 Using this document .24
Annex A (informative) Relevant parameters required for the chemical, physical and
biological characterization of materials for re-use .25
Annex B (normative) Good practice in the re-use of soil materials .35
Annex C (informative) Guidance on determination of the scope of investigation needed
before excavation of soil materials .39
Annex D (informative) Examples of classification and evaluation of soils and other soil
materials .41
Annex E (informative) Examples of elements and compounds belonging to different
contaminant groups .47
Bibliography .50
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 7,
Impact assessment.
This second edition cancels and replaces the first edition (ISO 15176:2002), which has been technically
revised. The main changes compared to the previous edition are as follows:
— introduction of references to the ISO 18400 series of standards;
— updated references to international standards.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved
Introduction
This document is one of a series providing guidance on the assessment of soils and soil materials in
relation to certain functions and uses. It should be read in conjunction with other International
Standards, some of which give more specific guidance in relation to some of the uses listed in the Scope
1)
or particular aspects of assessments. For example, ISO 15800 gives guidance on assessments relating
to human exposure to potentially harmful substances and ISO 15175 gives guidance on characterization
of contaminated soil related to groundwater protection.
Soils are the dynamic product of chemical, physical and biological processes. They are the result
of interactions between the inherent nature of the parent material, the prevailing environmental
conditions and human activities. They are a valuable natural and finite resource which should be
conserved wherever possible. When construction, mining or other activities require soils to be
excavated and moved from their natural situation, they should as far as possible be re-used in a manner
consistent with their natural properties and the intended use of the target location. Soils intended
for re-use are usually required to have certain chemical, leaching, geotechnical, physical, biological
and radiochemical attributes consistent with this future use. Particular attention should be paid in
situations where there is reason to believe that the soil might be contaminated.
Soils that are to be excavated, stripped, or otherwise removed from their original location, should be
investigated to determine how they can be re-used so as to minimize the quantities to be disposed of as
waste and to determine environmental impacts that might arise during re-use. Treatment of soils and
soil materials to remove or destroy contaminants or to reduce their availability to the environment can
alter soil properties. These properties should therefore be determined before re-use. For manufactured
soils, the characteristics of both the components and of the manufactured product might need to be
determined.
The purpose of characterizing soil (or other media) as suggested in this document is usually to enable
judgements to be made about its suitability for a defined use (e.g. arable farming, domestic gardens).
These judgements can be made by reference to published international or national guidance that sets
out physical, chemical or other generic criteria, or against criteria set on a site-specific basis. When
substances are present that might be harmful to human health or the environment, the judgement
can also be made on the basis of a site-specific qualitative, semi-quantitative or fully quantitative risk
assessment. In many jurisdictions, formal guidance on such assessments has been published. In some
cases this guidance fits within a legislative framework. Guidance has also been provided by professional
organizations and some standardization bodies.
When deciding whether to re-use soil material, other possibly competing or overriding objectives such
as protection of soil, nature, water and air; physical planning requirements and national legislative
requirements should be considered.
Assessment of soil material for re-use could require the measurement of the chemical, physical,
biological, geotechnical and radiochemical characteristics of soil material and of the source and target
sites. The assessor should identify those parameters that are appropriate to the task in hand.
This document identifies the functions and properties of soil materials at the source (point of origin) and
also the properties of the target (target) site which could be relevant to the potential uses listed in the
Scope and indicates for which parameters or procedures there are International Standards available.
Radiochemical and geotechnical aspects are not covered. For guidance on the geotechnical aspects of
the use of soil materials as construction material, see also other relevant International Standards (e.g.
those produced by ISO/TC 182, Geotechnics in the field of civil engineering) or national standards.
The way the soil is handled after excavation can affect soil properties. Some suggestions regarding good
practice in soil handling and related practice and monitoring after placement are provided in Annex B.
1) Under preparation. Stage at the time of publication: ISO/FDIS 15800.
INTERNATIONAL STANDARD ISO 15176:2019(E)
Guidance on characterization of excavated soil and other
materials intended for re-use
1 Scope
This document provides guidance on the range of tests that could be necessary to characterize soil and
other soil materials intended to be re-used, with or without preliminary treatment (e.g. screening to
remove over large material). It is intended to be of use in determining the suitability of soil materials for
re-use (see 3.4.1), and the assessment of the environmental impacts that might arise from re-use. It takes
into account the different requirements of topsoil, sub-soil and other soil materials such as sediments
or treated soils. International Standard methods are listed that might be of use for characterization.
Soil materials include natural soils and other materials (e.g. fill, made ground) excavated, stripped, or
otherwise removed from their original in-ground or above-ground location (e.g. stockpile), dredged
materials, manufactured soils, and soil treated to remove or destroy contaminants. For manufactured
soils, which are often made using excavated materials together with other materials such as “green
waste”, the characteristics of the components and of the manufactured product might need to be
determined.
NOTE The terms “excavated soil” and “excavated soil materials” are used for brevity throughout the
document to embrace the range of materials covered.
An overriding principle governing the guidance provided in this document is that when there is to be
no change in intended land use at the target site, imported soil materials cannot lead to a permanent
reduction in performance of relevant soil functions.
The guidance provided is intended to cover a range of possible end uses, including:
— play areas for small children, including nursery schools, kindergartens, etc.;
— schools;
— gardens and other residential areas;
— allotments;
— horticulture;
— agriculture;
— forestry;
— recreational areas, e.g. parks, sport fields;
— restoration of damaged ecosystems;
— mining and industrial sites;
— construction sites;
— road and rail constructions.
It is not applicable to the placement of soil materials in an aqueous environment or to restore
underground workings. It does not address geotechnical requirements when soil materials are to be
used as construction material.
NOTE The sensitive end uses listed above such as play areas for small children, schools, gardens,
agriculture and recreational areas require particular care, particularly when excavated soils are derived from
contaminated sites.
2 Normative reference
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1 Types of soil and other soil materials
3.1.1
soil
upper layer of the Earth’s crust transformed by weathering and physical/chemical and biological
processes composed of mineral particles, organic matter, water, gases and living organisms organized
in generic soil horizons
Note 1 to entry: In a broader civil engineering sense, soil includes topsoil and sub-soil; deposits such as clays,
silts, sands, gravels, cobbles, boulders and organic matter and deposits such as peat; materials of human origin
such as wastes; ground gas and moisture; and living organisms.
[SOURCE: ISO 11074:2015, 2.1.11, modified —"gases" replaces "air".]
3.1.2
topsoil
upper part of a natural soil that is generally dark coloured and has a higher content of organic matter
and nutrients when compared to the (mineral) horizons below, excluding the humus layer
Note 1 to entry: For arable land, topsoil refers to the ploughed soil depth, while for grassland; it is the soil layer
with high root content.
[SOURCE: ISO 11074:2015, 2.1.21]
3.1.3
subsoil
natural soil material below the topsoil and overlying the parent material parent rock beneath
Note 1 to entry: All or much of the original rock structure has usually been obliterated by pedogenic processes.
[SOURCE: ISO 11074:2015, 2.1.20, modified — "parent rock beneath" added.]
3.1.4
soil material
material composed of excavated soil, dredged materials, manufactured soils, treated soils and fill
materials
[SOURCE: ISO 11074:2015, 7.4.16]
2 © ISO 2019 – All rights reserved
3.1.5
excavated soil
soil material extracted from the ground
EXAMPLE Topsoil, subsoil, altered parent rock, typically arising during construction works.
[SOURCE: ISO 11074:2015, 2.2.6]
3.1.6
manufactured soil
manufactured product intended to perform specified soil functions produced by blending combinations
of natural, waste, or manufactured materials with the addition of nutrients or other additives, when
necessary
[SOURCE: ISO 11074:2015, 2.2.9, modified — "manufactured materials" replaces "soil materials".]
3.1.7
treated soil
soil that has been subjected to a process-based treatment method
[SOURCE: ISO 11074:2015, 2.2.16, modified — "process-based treatment method" replaces "ex situ or in
situ process".]
3.1.8
dredged material
solid material excavated or otherwise removed from waters, e.g. during maintenance, construction,
reconstruction and harbour or channel extension operation
Note 1 to entry: Dredged material might consist of sediment and soil taken from below the water surface.
[SOURCE: ISO 11074:2015, 2.2.4, modified — "material excavated" changed to "solid material excavated
or otherwise removed from waters" and "extension measures from waters" modified in "harbor or
channel extension operation". In note 1 to entry: "subhydric soils" deleted and "soil and their parent
material beneath the surface water body" changed to "soil taken from below the water surface".]
3.1.9
anthropogenic ground
deposits which have accumulated through human activity
2)
[SOURCE: ISO 11074:2015/DAmd 1:2019 ]
3.1.10
fill
anthropogenic ground in which the material has been selected, placed and compacted in accordance
with an engineering specification
[SOURCE: ISO 11074:2015/DAmd 1:2019]
3.1.11
made ground
anthropogenic ground comprising material placed without engineering control and/or manufactured
by man in some way, such as through crushing or washing, or arising from an industrial process
[SOURCE: ISO 11074:2015/DAmd 1:2019]
2) Under preparation. Stage at the time of publication: ISO 11074:2015/DAmd 1:2019.
3.2 Soil characteristics
3.2.1
soil functions
roles performed by soil that support ecosystems, the biosphere, the water environment and human
activities
EXAMPLE Control of substances and energy cycles as compartment of ecosystems, basis for life of plants,
animals and humans, basis for stability of buildings and roads, basis for the yield of agriculture, horticulture, and
forestry, carrier of genetic reservoir, document of natural history, archaeological and palaeological document.
[SOURCE: ISO 11074:2015, 3.3.31, modified — "roles performed by soil that support ecosystems, the
biosphere, the water environment and human activities" replaces "description of the significance of
soils to man and the environment".]
3.2.2
background concentration
concentration of a substance characteristic of a soil type in an area or region arising from both natural
sources and anthropogenic diffuse sources such as atmospheric deposition
[SOURCE: ISO 11074:2015, 3.5.1, modified — "anthropogenic diffuse sources" replaces "non-natural
diffuse sources".]
3.2.3
background value
statistical characteristics of the total (natural pedo-geochemical and anthropogenic) content of
substances in soil
Note 1 to entry: It is commonly expressed in terms of an average, median, or a range of values.
[SOURCE: ISO 11074:2015, 3.5.2, modified — Note 1 to entry added.]
3.2.4
natural background concentration
concentration of a substance that is derived solely from natural sources (i.e. of geogenic origin),
commonly expressed in terms of average, a range of values, or a natural-background value
[SOURCE: ISO 11074:2015, 3.5.7]
3.2.5
natural background value
statistical characteristics of the natural pedo-geochemical content of a substance in soils
[SOURCE: ISO 11074:2015, 3.5.8]
3.2.6
contaminant
substance or agent present in soil as a result of human activity
Note 1 to entry: There is no assumption in this definition that harms results from the presence of the contaminant.
[SOURCE: ISO 11074:2015, 3.4.6]
3.2.7
potentially harmful substance
substance which by its chemical form, concentration or presence, can be dangerous to humans or the
environment
Note 1 to entry: It can be present naturally or as a result of human activity.
[SOURCE: ISO 11074:2015, 3.4.19]
4 © ISO 2019 – All rights reserved
3.2.8
residual contamination
amount or concentration of contaminants remaining in a specific medium, following remediation
[SOURCE: ISO 11074:2015, 3.4.21]
3.2.9
trace element
element present in low concentration in soil material in respect to the most commonly observed natural
background level
[SOURCE: ISO 11074:2015, 3.5.12]
3.2.10
essential trace element
element essential at low concentrations for plant or animal (including human) metabolism
Note 1 to entry: An element can be essential at low concentrations but become harmful at higher concentrations.
[SOURCE: ISO 11074:2015, 3.5.5]
3.2.11
soil characterization
determination of relevant physical, chemical, and biological properties of the soil
[SOURCE: ISO 11074:2015, 2.1.12]
3.3 Land and sites
3.3.1
damaged land
degraded land
land which, due to natural processes or human activity, is no longer able to properly sustain an economic
function and/or its original natural ecological function
[SOURCE: ISO 11074:2015, 2.2.2]
3.3.2
target site
site at which soil is to be re-used
[SOURCE: ISO 11074:2015, 2.3.14]
3.4 Utilization, reclamation and treatment
3.4.1
re-use of soil material
useful and harmless utilization of soil materials
Note 1 to entry: Re-use can mean transfer of soil materials to another location for use in agriculture, horticulture,
forestry, gardens, recreational areas and construction sites.
[SOURCE: ISO 11074:2015, 2.2.12]
3.4.2
construction works
applications where soil materials are not required to have a direct productive use although they can
support other layers intended to have a productive use
Note 1 to entry: For example, including earthworks (e.g. embankments), landscape engineering, road
construction, construction of waste disposal sites, and backfilling of excavated sites or surface mines.
[SOURCE: ISO 11074:2015, 2.2.1, modified — "surface" added before "mines" in Note 1 to entry]
3.4.3
reclamation
rehabilitation
return of damaged, degraded or derelict land to beneficial use
Note 1 to entry: The term remediation is commonly restricted to the process of dealing with contaminated/
polluted sites.
[SOURCE: ISO 11074:2015, 2.2.11]
3.4.4
soil rehabilitation
action taken to improve the capability of damaged or degraded soil to perform specified functions (e.g.
addition of organic matter and nutrients to promote plant growth)
[SOURCE: ISO 11074:2015, 6.1.22]
3.4.5
remediation strategy
combination of remedial techniques and associated work programmes that will meet specified
contamination-related remediation objectives and other objectives (e.g. engineering related), and
overcome possible restraints
[SOURCE: ISO 11074:2015, 6.1.20, modified — "techniques" replaces "methods, "programmes"
added, "(e.g. residual contaminant concentrations)" removed, "possible restraints" replaces "residual
concentration"]
3.4.6
process-based treatment method
application of physical, chemical or biological processes either to remove or destroy contaminants, or to
reduce their availability to the environment
Note 1 to entry: Different treatment methods, e.g. biotreatment, are defined in ISO 11074.
3.4.7
stockpile
temporary deposit of soil material
[SOURCE: ISO 11074:2015, 2.2.14 modified — Note 1 and Note 2 to entry deleted]
3.4.8
investigation for compliance or performance
investigation, or programme of on-going inspection, testing or monitoring, to confirm that a remediation
strategy has been properly implemented and/or when a containment approach has been adopted, that
this continues to perform to the specified level
EXAMPLE Testing to confirm that all contaminated material has been removed.
3.5 Assessment
3.5.1
hazard
property of a substance or material, or situation that in particular circumstances could lead to harm or
pollution
[SOURCE: ISO 11074:2015, 5.2.15]
6 © ISO 2019 – All rights reserved
3.5.2
hazard
re-use of soil & soil materials
property of a substance or material, or any action that which might have an adverse effect on soil
functions
Note 1 to entry: A hazard has the potential to cause harm.
3.5.3
risk
combination of the probability and frequency of occurrence of a defined hazard and the magnitude of
the consequences of the occurrence
[SOURCE: ISO 11074:2015, 5.2.24]
3.5.4
harmlessness
condition in which the application of a soil material does not result in
damage, as defined by specific criteria, to the present functions of the soil already at the target site
[SOURCE: ISO 11074:2015, 5.2.14]
3.5.5
data quality objectives
statement of the required detection limits, accuracy, reproducibility and repeatability of the required
analytical and other data
Note 1 to entry: Generic data quality objectives are sometimes set at national level. Data quality objectives can
also embrace the amount of data required for an area of land (or part of a site) or for a stockpile to enable a sound
comparison with generic guidelines or standards or for a site-specific or material-specific estimation of risk.
[SOURCE: ISO 11074:2015, 5.1.2]
4 Characterization of soil materials and sites
4.1 General
The purpose of characterizing soil materials and sites intended for re-use of soil material is to enable
judgements to be made about their suitability for a defined use (e.g. arable farming, domestic gardens,
construction works). Before such judgements can be made, the right type, quantity and quality of
information and data shall be available (see Clause 5). It is necessary to determine relevant site
information and chemical, physical and biological soil and soil material characteristics as appropriate.
This requires the development of a soil management plan which should include:
— an investigation strategy (see 4.2) and, if necessary;
— sampling strategies (see 4.3) and, if necessary;
— analytical and testing strategies (see 4.4);
— and always an assessment framework (see Clause 5);
for each site, soil and soil material that is to be assessed.
Sometimes investigations are required for the sole purpose of deciding whether soil and other soil
material such as fill materials are suitable for re-use for a target site (see Figure 1) but this might
be only one of a number of objectives of a more comprehensive investigation of a suspect potentially
contaminated site. In this latter case, the initial task becomes to ensure that the overall sampling,
analytical and testing strategies for the investigation properly address the needs of this specific
objective. In practice, investigations are commonly phased for both technical and cost reasons and
it could therefore be preferable to carry out at least part of the characterization, particularly for
example of the nutrient and trace element status, physical and biological soil properties, through a
supplementary investigation (see Figure 2).
The guidance provided in this document focuses on soil materials that are to be excavated or have
already been excavated (e.g. have been placed in stockpiles). However, it also covers a number of other
situations including for example dredged materials, treated soil materials and manufactured soils.
Comparable investigation is required in all situations to ensure a good understanding of the source of
the material and its components so that appropriate analytical and testing strategies can be developed.
NOTE 1 In some jurisdictions and some circumstances, any excavated material could be considered to be
waste for regulatory purposes. There could be set procedures to go through to avoid such classification and/or
enable the excavated material to be re-used. These can be accompanied by prescribed assessment procedures
and testing regimes. These do not necessarily yield analytical results etc. that can be used for assessment for
re-use as described in this document. Similarly, there can be regulatory procedures to follow when excavated
materials are to be used for construction purposes.
Care should be taken during site investigation and subsequent handling of soil materials intended to be
re-used to avoid the spread of invasive and noxious plants, infective agents, destructive organisms, and
genetically modified (GM) crops outside of areas approved for their growth (see also ISO 18400-103).
NOTE Examples relevant to temperate climates include: invasive and noxious plants - Japanese Knotweed
(Fallopia japonica), infective agents - those causing, foot/hoof and mouth disease (Aphatae epizooticae) and
Rhizomania [Benyvirus – Beet Necrotic Yellow Vein Virus (BNYVV)].
8 © ISO 2019 – All rights reserved
Figure 1 — Overall flow chart for characterization of soil materials for re-use
4.2 Investigation strategies
Before investigation of the soil or soil material is started, it is essential to define the objectives of the
investigation.
In general, there are three likely situations:
a) the presence of elevated concentrations of potentially harmful substances (e.g. above background
values) or unacceptably high nutrient status in the soil material can be excluded on the basis of the
available information;
b) the soil material originates from an area with natural high concentrations of potentially harmful
substances and/or organic and/or sulfidic level;
c) there are indications that anthropogenic activities have resulted in elevated concentrations of
potentially harmful substances, i.e. the soil material is contaminated.
The typical overall investigation strategy for a potentially contaminated site (i.e. one where it is
suspected potentially harmful substances could be present as a result of human activity) or one where
there are naturally elevated concentrations of potentially harmful substances is to:
— carry out a preliminary investigation in accordance with ISO 18400-202 comprising a desk-top
study and a site reconnaissance (walk over-survey) – the aim is to build up a comprehensive picture
of the history of the site, its geology and hydrogeology, environmental setting, current condition;
3)
and, on the basis of the resulting conceptual site model (see ISO 21365:2019 ), to:
— develop a strategy for intrusive investigation in accordance with ISO 18400-203 which properly
takes into account the health and safety of the investigation team and the general public, and which
avoids harm to the environment.
Often, the intrusive investigation will be phased (see Figure 2). An initial exploratory investigation
(Phase 2) can be carried out first to confirm or to refute hypotheses drawn from the preliminary
investigation (Phase 1) and to provide initial information to be better able to design the subsequent
detailed investigation (Phase 3). In the light of the results of these early phases, it could be necessary
to carry out supplementary investigations (Phase 4) to determine, for example the suitability of soil for
re-use, or to gather information relevant to the application of a process-based treatment method.
It is important that the information and data required to assess excavated soil material for re-use is
identified as far as possible before the investigation starts. In this way appropriate sampling, analytical
and testing strategies can be developed at the outset. If this is not done, there can be significant gaps in
the information available, necessitating further costly intrusive investigation. However, some aspects
of characterization might often be better addressed through a supplementary investigation.
Each intrusive investigation should be accompanied by on-site observation of the site and soil material
including appropriate description and documentation.
The approach outlined above should be adapted for other sources of soil materials, for example when
soil material is being manufactured it would be appropriate to enquire into the source and history of
each of the ingredients. In the case of soil material from a process-based treatment method, it would be
appropriate to enquire into the history of the source site. Exploratory sampling programmes could then
be carried out before designing and embarking on a programme for continuous monitoring of feed and
output materials.
NOTE Sites sometimes contain “hotspots”, i.e. areas where the concentrations of potentially harmful
substances are higher than for the generality of the site. Generally, an excavation plan is needed that excludes
the material from such “hot-spots” from that exported from the site for re-use. As noted in ISO 18400-104 8.2.3,
a hot spot can be designated as (i) an area of contamination in an otherwise uncontaminated area, or (ii) an
area of much greater contamination in a site that is generally contaminated. The size of a hotspot is not a fixed
parameter and depends for example on what concentration of a particular contaminant is judged noteworthy
when assessing the results of the investigation. This might be a generic assessment criterion appropriate for the
intended use of the soil.
4.3 Sampling strategies
4.3.1 General considerations
Investigation could be required (as appropriate):
a) at the point of excavation;
b) of excavated material in a stockpile;
c) following treatment of excavated soil or soil material;
d) of manufactured soil;
3) Under preparation. Stage at the time of publication: ISO/DIS 21365:2019.
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e) at the target site.
The sampling strategies and the measurements to be made (analytical and testing strategy) should be
determined on the basis of:
f) the history of the site from which the soil material is excavated or dredged;
g) available data or results of previous investigations;
h) the nature and type of material to be characterized;
i) the quantity of soil material to be assessed;
j) the nature of any process-based treatment methods that has been applied to the soil material;
k) the intended use of the soil material;
l) the planned way of handling the soil material from excavation to target site, e.g. transport and
stockpiling;
m) the history and present condition of the target site;
n) the intended use of the target site;
o) data quality objectives (see Clause 5).
NOTE Further guidance on site investigation relevant to re-use of excavated materials is provided in Annex C
Figure 2 — Diagram showing how assessment of excavated soil material might fit into
investigation of a suspect potentially contaminated site (as opposed to the alternative of a
dedicated investigation with this sole objective)
When deciding on investigation, sampling, analytical and testing strategies, authoritative guidance
applicable in the jurisdiction where the soil is to be excavated and/or re-used should be followed.
Reference should be made to relevant International Standards and to the guidance attached to any
national guidelines or standards relating to soil quality that are to be used in the assessment of the
results of the investigation. In some jurisdictions, there could be a legal requirement to follow certain
procedures if published criteria are to be used as the basis of the assessment.
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Within the scope of this document, sampling might be required of in situ or excavated (ex situ) soil, fill
materials, dredged materials, manufactured soils and the components thereof, and treated soils. For
example:
— in situ soils and other materials intended for excavation;
— in situ soils at the intended location of use;
— groundwater at the point of excavation or at the point of re-deposition or surface water in contact
with sediments (see 4.3.8 and the Note below);
— sediments in situ in ponds, lakes, canals, estuaries etc.;
— stockpiles of excavated soils and other soil materials;
— stockpiles of excavated sediments;
— soil materials arising from a process-based remediation method;
— in situ soil, etc., after emplacement, to ensure conformance and performance.
NOTE Determination of groundwater levels and their fluctuation over time might be required in some
circumstances, e.g. to guide decisions about how deep to excavate. Water quality in contact with sediments etc.
could be important in relation to how to deal with any water draining from the sediment after extraction.
International Standards should be applied for sampling soils in various contexts; these are published as
parts of ISO 18400. International Standards are also available for sampling surface water (ISO 5667-4,
ISO 5667-6), groundwater (ISO 5667-11), and sediments (ISO 5667-12). In the absence of appropriate
International Standards, appropriate national or equivalent standards should be used.
In general, soil materials should be sampled in situ rather than after placement in stockpiles. This
enables potential environmental impacts arising from handling and storage to be determined, and
potential damage to the soil that might arise during storage to be avoided (see Annex B).
Whilst the testing of soils for geotechnical properties is outside of the scope of this document, the
guidance available for description, sampling and investigation design can sometimes be helpful.
In particular, attention is drawn to ISO 14688-1, ISO 14688-2 and to ISO 14689. These International
Standards include definitions (e.g. of soil and rock) specific to geotechnical applications.
4.3.2 Sampling in situ soil materials
If sufficient data are not already available, it will be necessary to sample soil materials at the point of
excavation and/or at the target site.
On-site screening methods should be used when appropriate (see for example ISO 12404 and 13196).
Relevant International Standards on sampling soils in relation to soil quality are listed in the
Bibliography. The principal guidance on sampling strategies is provided in ISO 18400-104.
NOTE On-site screening methods might for example be particularly useful where investigations to date have
shown that contamination is variable across the site and that only a portion is fit to use for the intended purpose.
Application of an on-site XRF method (e.g. ISO 13196) could enable the areas from which soil may be re-used to
be more closely delineated, monitoring as material is removed from site, and monitoring at the target site.
4.3.3 Sampling sediments
Guidance on sampling of sediments is given in ISO 5667-12.
4.3.4 Sampling stockpiles of untreated or treated soil materials
Soil materials are sometimes stockpiled after excavation or dredging, as are treated materials. Special
sampling methods are required for such stockpiles (see ISO 18400-102). Samples from different
stockpiles should not be mixed.
NOTE Guidance on sampling strategies for stockpiles and other above ground deposits is provided in
ISO 18400-104.
4.3.5 Sampling materials arising from a process-based remediation method
Assessment of materials arising from a process-based treatment method usually requires sampling at
the time of production in a statistically sound way in order to confirm conformance with pre-determined
chemical, physical or biological criteria (for example residual concentrations of contaminants).
Sampling can be done from stockpiles or from the production line.
NOTE Guidance on sampling strategies for stockpiles and other above ground deposits is provided in
ISO 18400-104.
4.3.6 Sampling manufactured soils
Assessment of manufactured soil materials usually requires sampling in a statistically sound way
in order to confirm conformance with pre-determined chemical, physical or biological criteria. This
sampling can be done from stockpiles or from the production line.
The materials used in manufacture
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